With regard to receiver systems for transmitting information to an otological device, particularly a hearing aid, for example by means of an accessory part, particularly a remote control, a programming unit or a comparable device, or from the otological device to another otological device or an accessory part, for example a remote control or a programming unit, correct tuning of a resonant frequency for an oscillation receiver of the receiver system is required since incorrect tuning of the resonant frequency has a major influence on a transmission quality or on an achievable transmission range. Normally, a frequency response of a receiver system has a bandpass characteristic with a center frequency, whereby the center frequency should be set as precisely as possible at a receive frequency provided for transmission purposes. A receive frequency for such a receiver is essentially determined by frequency determining components such as coils, capacitors or components connected thereto. Such components can exhibit tolerances of a predefined component value, which means that an initial tuning is necessary in order to specify a receive frequency. Furthermore, temperature- and ageing-related changes in the frequency determining components can render necessary a retuning.
With regard to radio receivers known from the prior art, a receive frequency can be tuned manually by a user. In addition, quartz-stabilized PLL receivers for example are known which require no retuning of a receive frequency (PLL=phase locked loop).
A quadrature modulation receiver is known from JP10013191A2 which is designed to change, and thus to retune, a receive frequency of the receiver circuit depending on a signal strength of a receiver circuit.
A PLL receiver, described above, can for example only be used with difficulty, or not at all, in otological devices, particularly hearing aids or in an accessory for hearing aids on account of a space requirement or a power consumption.